Laser desorption techniques will be developed for mass spectrometric analysis of nonvolatile organic molecules adsorbed on solid surfaces. These techniques are suitable for combination with both high performance liquid chromatography and thin-layer chromatography and should provide both molecular weight and structural information on a wide range of biologically important compounds which are difficult or impossible to analyze by mass spectrometry using presently available techniques. In addition to instrument development, fundamental studies will be conducted of the processes leading to desorption of intact molecules and ions from solid surfaces. These studies include detailed measurements of the properties of the plume produced by an intense laser pulse impinging on a surface and direct comparisons of the mass spectra and energy distributions of the ions produced by laser desorption with those produced by other desorption techniques including SIMS, rapid thermal heating, in-beam CI and EI techniques, and macroscopic charged particle impact. We anticipate that the results of the proposed research will include a better understanding of the processes involved in producing ions by desorbing nonvolatile molecules from surfaces and substantial improvements in the utility of mass spectrometry for applications to nonvolatile biological samples including new practical techniques for combined LC-MS and TLC-MS.